On the 24\" iMac I\'m using at work I cannot scale the iOS Simulator\'s window. The 100% and 50% menu entries are greyed out (and the keyboard shortcuts don\'t work either.)
Even in xcode9 it won't let you set the scaling to 100% if your screen can't accommodate that, but you can cheat.. ..just choose landscape orientation and if the width of the device will fit the height of the screen, you can choose 100%, and then rotate the device even if it won't all fit on screen.